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Method and apparatus for entity authentication

  • US 5,481,611 A
  • Filed: 12/09/1993
  • Issued: 01/02/1996
  • Est. Priority Date: 12/09/1993
  • Status: Expired due to Term
First Claim
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1. A method of authenticating a user attempting access into a host facility from a remote subscriber site, comprising the steps of:

  • generating a challenge code including a random digital sequence at the host;

    encrypting the challenge code by cryptographically applying a key code to said digital sequence to produce a host-encrypted code;

    transmitting a modified version of the challenge code by encoding said challenge code into a dual-tone-multi-frequency (DTMF) signal format suitable for transmission to a first electronic device at the subscriber site; and

    acoustically coupling the DTMF signal received at the first electronic device at the subscriber site onto a transmission medium in operable communication with a second electronic device at the subscriber site;

    encrypting the challenge code at the second electronic device at the subscriber site to produce a user-encrypted code;

    transmitting by the second electronic device the user-encrypted code to the first electronic device and transmitting by the first electronic device the user-encrypted code to the host; and

    comparing at the host the user-encrypted code to the host-encrypted code and, if a match is found, permitting the user to access the host.

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